Correlations between fluoride concentration, sample weight and acid production in dental plaque from children

Abstract

Plaque was collected from 60 children aged 7 yr who were participating in a short-term study on the effect of fluoridized milk on plaque F. Plaque F was unaffected by 1 or 5 parts 10 6 F in milk. Correlations and partial correlations were calculated between: plaque weight, plaque F and the initial and final pH of plaque/sugar incubations. The mean (±SD) plaque weight was 10.1 mg (±4.83) and plaque F (wet weight) was 3.5 parts 10 6 (±1.79). Plaque F was significantly correlated with final pH ( r = +0.42; p < 0.01) but the correlation was of border-line significance ( r = +0.23; p = 0.06) when data were standardized on weight. Plaque F and weight were significantly correlated ( r = −0.33; p < 0.05). The correlation between weight and final pH ( r = −0.64; p < 0.01) was little affected by standardizing the data on initial pH or plaque F. The results indicate the importance of considering the weight of plaque when comparing F concentration or pH changes in plaque. The findings do not cast doubt on the validity of earlier results suggesting that pH falls were smaller in plaques from high fluoride areas because there is no evidence that fluoridated water reduced plaque weight.